Means for preventing retrograde motion of an automobile



July 2, 1935. R. LAPSLEY 2,006,398

VENTING RETROGRADE MOTION OF AN AUTOMOBILE Filed Sept. 28, 1929 3Sheets-Shet l MEANS FOR PRE July 2, 1935. R. LAPSLEY 2,006,398

MEANS FOR PREVENTING RETROGRADE MOTION OF AN AUTOMOBILE Filed Sept. 28,'1929 5 Sheets-Sheet Z I b m 4-1,, v I im M 2, 1935. LAPSLEY 2,006,398

MEANS FOR PREVENTING RETROGRADE MOTION OF AN AUTOMOBILE Filed Sept. 28,1929 3 Sheets- Sheet s in ss n fla /w P? W Y Kio a Patented July 2, 1935UNITED, STATES,

MEANS FOR PREVENTING RETROGRADE,

- MOTION OF AN AUTOMOBILE Robert Lapsley, Berrien SprihgsQMiclL,assignor I to Clark Equipment Company, Buchanan,

Mich., a corporation of Michigan.

Application September 28, 1929, SerialNo. 395,799

' 16 Claims. (01. 192-4) 7 1 may happen to be behind it. This is aparticulardisadvantage when the automobile is being driven in heavytraffic and is stopped by traffic conditions, since under theseconditions there are invariably cars immediately behind it. v Theapplication of the brakes and necessity of holding them engaged untilthe car is startedforward again makes the starting of the car moredifficult and in the case of an inexperienced driver frequently resultsin a stopping of the engine and consequent tie-up in the traffic of thatstreet.

Moreover this tendency of a car to roll backward when on an inclineconstitutes a hazard of considerable moment if the'engine of the carisstopped on a steep hill, for under these circumstances extreme skill onthe part of the driver is required to restart the motor and to restartthe car up the hill.

In recognition of this difiiculty and as a pos sible solution of it,devices have been made here tofore, of which I am aware, in whichtheautomobile is definitely prevented from retrograde motion except whenits gears are placed in position to drive it in a backward direction.That is, while the car is in neutral or one of its forward speeds, it iscapable only of advancing and any tendency on the part or the car toroll backwards is stopped by the means employed to prevent retrogrademotion of the car. In order to facili- 40 tate backing the car when itis necessary to do. so, means are provided in connection with the gearshift and lever for shifting it such thatthe retrograde preventingdevice is disabled while the reverse gear is engaged.

This device, while it is of material benefit in. that it preventsunwantedretrograde motion or the car, is subject to the seriouscriticism thatin case the car hasbeen shifted into 'reverse and startedbackward, and the reverse gear disen' ,gaged while the car is'stillmoving backward, the retrograde preventing means immediately engageswith the consequent jerking of thecar; and in some instances this hasresulted indamage to the'gears of the car. I V In my present invention Ihave provided a new and improved means for pr'eventingretrograde motionof the car, a means which is normally effective when the car is inneutral or any of its forward speeds, and ineffective when-the car is inreverse or in neutral following a movement in reverse. Under the lattercircumstances, the retrograde motion preventing means is ineffectiveuntil the car has again been moved forward.

The addition of the device of my invention to an automobile adds no newfunctions or operations for the driver to perform but rather it isentirely automatic inits operation and its oper-' ation makes thedriving of the car easier rather than more difficult.v I 5' A carequipped with the device of my invention and operating on anincline'is'positively prevented from rolling backward ifthe enginestops, or-the gears are disengaged to bring the car to a'halt undertrafiic conditions. The driver need notsetl the brakes to prevent thecar from rolling backward and therefore can confine his entire atten;

tion to restarting his motor or restartinghislcar as the case may be.

Moreover, the-device of my invention while it positively preventsretrogressive motion of the car when that motion is. not wanted,instantly yields to aslight pressure on the gear shifting rod to shiftthe reverse gears into engagement, and that yielding disables thedevice.

The retrograde motion preventing device of my invention is applicable totrucks, tractors, shop tractors and the like, in fact to any automobilevehicle, whether: it be driven by an internal com bustion engine, asteam engine or an electric motor. In these latter types of vehicles,because of the absence of change of speed gears, the device q of myinvention may be connected to and operated by the reverser mechanism ofthe vehicle. Thus in a steam driven vehic1e,the device maybe associatedwith the Stevenson link, and in an electrical vehicle with the reverserswitch. Theinvention has great utility in pleasure cars since it adds tothe safety; of those cars, particularly whenthey are driven byrelatively inexperienced drivers. The device is also of great utilitywhen applied to contractors service trucks which are employed in thetransportation of materials on a construction project becauseof theirregular roadway over which such vehicles must travel and theprevalence of grades in that roadway.

No additional effort is required on the part of the driver to shift intoreverse because of the presence of the. retrograde motion preventingdevice and disablement of it by the shift into reverse, since PAT NTOFFICE I? the disablement is effected by a movement of simple parts.

In the preferred embodiment of my invention I provide a ratchet wheelsplined to the drive shaft wheel, and when the car is driven backwardby.

the reverse gears, a locking device maintained in frictional engagementwith the ratchet wheel a is rotated to lock the pawl out of engagementwith the teeth of that wheel. Should the reverse gears of the car bedisengaged while the car is stilLmoving backward, the lock prevents thepawl from reengaging the teeth of the ratchet wheel. This arrangementpermits the car to continue in a back ward direction even after itsreverse gears have been disengaged, this freedom to move backwardscontinuing until the car has been again moved f orward at ,whichtime thelock is moved out of engagement with the pawl by itsfrictional'engagement with the ratchet which isthen moving in itsforward direction.

Now to acquaint those skilled in the art with the teachings of myinvention, reference is made to the accompanying drawings in which apreferred embodiment of it is illustrated by way of example, and. inwhich:

Figure l is a side view of a transmission with a part of the casing cutaway to disclose a part of the gears and the retrograde motionpreventing device contained therein;

Figure 2 is a cross sectional view of Figure 1 taken substantially alongthe line 22 looking in thedirection of the arrows.

Figure 3 is a cross sectional view of Figure 1 takensubstantially alongthe line 3--3 a1so looking in the direction of the arrows; V

Figure 4 is a perspective View of the pawl'that engages the'teeth of theratchet wheel to prevent retrograde movement of the car;

,Figure 5 is a perspective view of the lock for retaining thepawldisengaged from the ratchet;

and

Figure 6 is a cross sectional view of a different type of transmissionshowing the application of my device thereto.

Referring to the drawings now in more detail; the transmission casing lis formed in substantially the same manner as is customary intransmissions of this type, and houses the' usual gears and shaft andlevers employed in the control of the vehicle. as an integral part ofthe clutch housing 2 and fitted in the vehicle immediately to the rearofthe motor.

Because of the inclusionof the device of m'y invention in thetransmission casing I, it is ne'ce's-- sary that that casing be slightlylonger than the ordinary transmission casing, that is, the rear wall 3is moved back sufficiently to permit the addition of my device in thecasing.

The transmission shown in Figures 1 'and"2 is a transmission of the fivespeed'type in which there are four speeds forward and one in re}. verse.To control the gears of the transmission three shift rods 4, 5 and 6 areprovided and the shift lever 1 arranged to selectively engage these rodsto move them forward and backward Preferably this casing l is formed toselectively engage the various gears of the transmission.

In transmissions of this type, the reverse rod, 6, moves in onedirection only, and the forward speed rods 4 and 5 move both forward andbackward.

'In the transmission shown the shift rods 4, 5

and '6 are supported in the cover 26 which is aligned on the casing l bythe dowel pins 21 and held thereon by a plurality of bolts 28. This 'orany other preferred type of construction can be employed in themanufacture of transmissions containing the :device of my invention andthe particular type illustrated is shown by way of example only.

' Within the transmission casing is the drive shaft 8 with which thepropeller shaft driving the vehicle is connected and upon which gears 9and it) are splined and adapted to be moved longitudinally of the shaftby the fork ll engaging the shoulder I2 on those gears. This fork I l isfastened on to one of the shift rods in such a manner that it may becontrolled by a movement of the lever I. v

The particular arrangement of the gears and order of their movement toplace the transmission in any one of its various speeds is not of theessence of the present invention as my invention can be employed in anyexisting type of transmission. p

The drive shaft 8 projects rearwardlyof the transmission and issupported-by the bearing l3 disposed in a suitable recess M in the rearwall 3 of the transmission casing, that hearing being means in thetransmission casing I place the ratchet wheel 20 upon the splinedportion of the shaft 8 and lock it against longitudinal move ment onthis shaft by a key 2| projecting through shoulder '22 of the ratchetwheel and engaging a keyway in the shaft. The wheel 2 is provided withteeth 23 which engage the splined portion of the shaft to preventrotation of the ratchet wheel with respect to the shaft.

The ratchet wheel is also provided with a plurality of teeth'24 theradial face '25 of which trails behind the sloping face '26 as'theratchet is rotated by a forward movement of the'car, that rotation beingcounter-clockwise as seen in Figure 2.

'The pawl 30 is mounted upon the pivot rod 3| which is 'fitted intosuitable bosses, not shown, provided in the projection 33 of the sidewall of the transmission casing.

This pawl 30 is provided with a central generally circular opening 34which fits around the ratchet wheel 20. Within this opening teeth 35 and31 project, the former to engage the radial face 25 of the teeth of theratchet wheel to prevent reverse rotation of the ratchet wheel, and. thelatter tooth 31 to ride over the sloping faces 26 of the teeth of theratchet wheel to prevent the pawl from making a noise as the ratchetwheel is rotated by forward movement of the vehicle. a On the outsidesurface of the pawl 39 I provide cars 38 and 39 which form a support forthe 2,006,398 pivot 40 which'projects therethrough to attach the link 4!to the pawl. This link projects up wardand is provided with a circularopening 42 through which the reverse shift rod 6 is projected, Thereverse shift rod 6 is provided with a cam-like portion 43 so locatedthatwhen the rod is in its normal position as shown in Figure 1, thelever 4| rides down in the hollow part of the cam and permits the pawl30 to rotate aboutits pivot 3| to bring the tooth 36 into engagementwith the teeth of the ratchet 20, When-the shift rod-6 is moved to itsoperative position to engage the reverse gears l I of the transmission,the link 4| rides up over the high part 44 of the cam 43 to'raise thepawl 30 and thereby bring the tooth 36 out of engagement with theteethof the ratchet wheel.

In Figure 2 the pawl is shown in its raised position, that is with thelink 4| disposed upon thehigh portion 44 of the cam 43.

The lower part ofthe opening 34 in the pawl 30 is shaped as the arc of acircle that is substantially concentric with the axis of the shaft 8when the pawlis raised, and the teeth 24 of the ratchet wheel slide overthis surface when the pawl .is raised. The upper part of the opening 34is extended at 35 to provide clearance around the teeth 36 and 31.

The pawl 30 is also provided with the projecting ear or boss 45 whichcooperates with the lock-' ing disc to hold the pawl in its raisedposition, in a manner that will be subsequently explained. The lockingdisc 50 is provided with a circular central opening 5| which enables itto be fitted around the shaft 8 and to abut against the rear face of theratchet wheel 20. The disc is also provided with the ball race 52 inwhich the balls of the thrust bearing 54 are fitted.

The stationary member 55 of this thrust bearing comprises a disc alsohaving a central opening 56 to permit it to be fitted around the shaft8. A plurality of dowels 59 are attached to the stationary plate 55 andproject into circular pockets 60 disposed'in the flange 6| of the rearwall 3 ,of the transmission casing, the dowels preventing rotation ofthe stationary bearing member 55. Springs 62 disposed in the pockets 60and bearing against the ends of the dowels 59 tension the bearing tothereby hold the locking disc50in frictional engagement with the rearface of the ratchet wheel 20.

The locking disc is provided with the radial shoulder 63 adjacent to theslotted portion 64, and with the shoulder which forms a cam raised fromthe surface of the slotted portion 64.

As will best be seen in Figure 3,,when the ratchet wheel 20 is rotatedin a counter-clockwise direction as the drive shaft 8 is driving thevehicle forward the disc 50 through its frictional engagementwith thisratchet is rotated counter-clockwise until the shoulder 63 strikesagainst the car 45 on the pawl 30 to prevent further rotation of thedisc. With the ear 45in this position, the pawl is free to'move up anddown to permit its tooth 36 to'engage the teeth 24 of the ratchet wheel.The width of the slot 64 is suchthat the car 45 freely slides in and outof it.

When the car is shifted into reverse and the pawllifted by a forwardmovement of the shift rod 6, ear 45 moves upward into the positioninwith that ratchet, to bring the shoulder 65 under the lower surface ofthe ear 45, thereby locking the pawl in its nonoperating positionindependently of the link 4| and cam 43 engagedthereby. With the lockingdisc 50 in this position, the pawl is locked out of engagement with theteeth of the ratchet-wheel so that backward movement of the vehicle maycontinue indefinitely. In order that the pawl may be returned to itsoperating position in which it iscapable ofengaging its tooth 36 withthe teeth of the ratchet wheel to stop a backward movement of the car,it is necessaryto again move the car forward so that the locking disc50may be rotated in a counterclockwise direction by itsfrictionalengagement with the ratchet 20 ,to move the shoulder 65 out from underthe ear 45, that rotation of f the disc 50 o ontinui f ,until the ear 45again strikes the revolve in' a clockwise direction for a distancegreater than the circular pitch of its teeth before the shoulder 65 isbrought into engagement with theunder surface of the ear 45.

. With the pawl 30 in its operating position, that is down with thetooth 36 capable of engaging the teeth of the ratchet wheel, the maximumreverse rotation that the ratchet wheelcan make is approximately thewidth of one tooth, therefore under the circumstances in which the pawlis'in its operating position, it is impossible for the vehicle tomovebackwardssufficiently far to rotate the'locking disc sufficiently tobring the shoulder 65 under the ear 45, since the tooth 36 of the pawlwill engage a tooth of the ratchet wheel and stop the retrograde motion.This insures that the pawl will be operatively engaged with the ratchetwheel to prevent retrograde motion of l the car at all times except whenthe car is in reverse gear and immediately after that and before it hasagain been driven forward.

. As will best be seen in Figure 2, when the ratchet wheel 20 is rotatedin a counter-clockwise direction by the shaft 8 driving the car forward;

the tooth 31 on the pawl 30 engages the sloping faces 26 of the teeth 24and rides over those-surratchet teeth the ratchet tooth engages thesloping surface 66 of the tooth 3'! permitting the pawl to descendslowly, that descent continuing until the opposite surface of the tooth31 engages the sloping face 26 of the next ratchet wheel tooth.

By'this arrangement when the car is running forward, the pawl rides overthe teeth of the ratchet wheel without making an appreciable noise,thereby insuring that the operation of the car will not be madenoisybecause of the addition of the retrograde movement preventing device. I

The transmission shown in Figures 1, 2 and 3, is a five speedtransmission in which the sap. arate reverse shift rod 6 is movedforward to engage the reverse gears of the transmission. In such atransmission the cam 43on the shift rod is positioned withits lowportion forward and its high portion 44 to the rear so that as the,

lift the pawl out of engagement with the ratchet 50- When the wheel. InFigure 6 I have shown a portion of a transmission, in which the shiftrod is moved to the rear, that is to theright in Figure 6, to engage thereverse gears of the transmission. In Figure 6 the rod 70 is shown inthe'posi tion that it assumes when the reverse gear is engaged. The camH is disposed with its high portion 12 ahead of its low portion 13 sothat as the shift rod is moved backward the link-4| is raised from thelow portion 13 to the high portion 12 of the cam. r

The particular pawl and link arrangement shown in the drawings is shownby way of example only as there are many modificationsin the design ofthese parts that can be made within the teachings of my invention,'-andI am not therefore to belimited to the specific details shown. Theinvention is applicable to any transmission and any one of a largenumber of specific arrangements may be employed in'that application.However, I prefer to lift the pawl by the link 4| as shown in thedrawings since it isfdesirable that the addition of the retrogradepreventing device be designed so that its inclusion in the transmissionadds nothing to the operating routine of the car. By providing the link-4| cammed onto the shift rod 5 and employing that link to raise the pawl39 in the manner shown, the pawl can be-thrown out of engagement withthe teeth of the ratchet wheel without adding any appreciable drag onthe gear shift lever 1 as the car is being thrown into reverse. That is,the link 36 being pivoted to move freely can be easily raised by the camon the gear shift rod 5 and the force required to raise this link is sosmall that an only inappreciable load is added to the gear shift rodlever l. v

Having thus complied'with the statutes and shown and described apreferred embodiment of my invention, what I consider new and desire tohave protected by Letters Patent is pointed out in the appended claims.

What is claimed is: i i

1. In a motor vehicle, a shaft normally rotat able in one direction andprevented fromrotating in the opposite direction by a ratchet ontheshaft and a pawl engaged thereby, means for :dlS- engaging said; pawl topermit rotation of said shaft in the opposite direction, andmeanscontrolled by a rotation of such shaft in said opposite direction forlocking said pawl disengaged from said ratchet until the shaft isagainrotated in said one direction.

2. In combination with a shaft driven forward by gears, a reverse gearadapted todrive said shaft in a reverse direction, a rod shifted endwiseto engage said reverse gear with said shaft, a ratchet wheel on saidshaft, means cooperating therewith to prevent a reverse directionrotation of the wheel and shaft, a lever moved by said rod when it ismoved to engage said reverse gears with said shaft to disengage saidcooperating means to permit a reverse rotation of said shaft,

and means for locking said cooperating means disengaged independently ofsaid lever.

3. In amotor driven vehicle having a transmission provided with drivingand driven parts operable in neutral and forward and'reverse di-,rections for the control of the. vehicle, one of said parts including ashaft for driving the vehicle, means for preventing retrogrademovementof the vehicle when said transmission is in its neutral" orforward positions, means for permitting retrograde movement of thevehicle when; said transmission is in its reverse position, and means infrictional engagement with one of the driven parts for causing said lastmeans to continue to be effective until the shaft rotates in-a forwarddirection.

4. In a transmission, a shaft driven thereby to drive a" vehicle, gearscooperating with the shaft to drive it in a forward direction, othergears cooperating therewith to drive it in a reverse direction,selective means controlling said gears, a ratchet on said shaft, a'pawlarranged to engage said ratchet to prevent rotation of said shaft in areverse direction, means control-led by said selective means fordisengaging said pawl to permit reverse rotation of the shaft, and meanscontrolled by that reverse rotation for holding said pawl disengageduntil the shaft is again driven forward. i

5. In a motor driven vehicle, a transmission casing, a drive shaftprojecting through one wall thereof, gears within said casing arrangedto be selectively controlled to drive said shaft in forward and reversedirections, shift rods for controlling said gears, one of said rodsbeing moved longitudinally to connect the reverse gears with said shaft,a ratchet wheel splined to said shaft, a pawl pivoted to the wall ofsaid casing and engaging the teeth of said ratchet wheel to preventreverse rotation of said shaft, a lever pivoted to said pawl andengaging a cam on said shift rod and lifted thereby to disengage thepawl when said rod is moved to connect the reverse gears to said shaft,a cam loosely fitted on said shaft and rotatable thereabout, a thrustbearing having a stationary member disposed on the wall of said casingthrough which said shaft projects concentrically of said shaft and amovable member holding said cam in frictional engagement with saidratchet, said cam being rotated by a reverse rotation of said ratchet,tov hold the pawl out of engagement therewith independently of saidlever and rotated by a subsequent forward movement of the ratchet toreengage the pawl with the ratchet.

6. In a motor drivenvehicle, thecombination of a transmission havinggears selectively engaginga shaft to drive the vehicle in forward andreverse directions, with a pawl and ratchet for pre-. venting a reversemovement of said vehicle while said gearsare set to drive it forward,means. for disengaging said pawl from said ratchet when said gears areset to drive the vehicle in a reverse direction, and a collar looselyfitted around said shaft and rotated by a reverse movement thereof tolock said pawl disengaged from said ratchet independently of said gearsand rotated by a for'-. ward movement of the shaft to unlock the pawland reengage it with the ratchet.

'7. In a motor driven vehicle, the combination: of a transmission havinggears selectively engaging a shaftto drive the vehicle in forwardandreverse directions, with a pawl and a ratchet for preventing a reversemovement of the vehicle when said gears are set to drive it forward,means for disengaging said pawl from said ratchet when said gearsare setto drive the vehicle in a reverse direction, a collar loosely fittedaround said shaft and held in frictional engagement with said ratchet,an car on said pawl, and'a cam on said collar brought into engagementwith said eat when said collar, is rotated by a reverse movemerit ofsaid vehicle to maintain the pawl disengage-d from the ratchet until theshaft rotates in a'forward direction.

J "3. The combination of a'shaft having aratchet wheel mounted thereon,said ratchet wheel having a plurality of teeth, with a pawl having twoteeth one of which engages the teeth of said ratchet during a normalrotation of the shaft to hold the other pawl tooth disengaged from theratchet teeth, and said other pawl tooth engaging a tooth of the ratchetto prevent a rotation of the shaft in a direction opposite to saidnormal rotation.

9. The combination of a shaft having a ratchet wheel mounted thereon,said ratchet wheel having a plurality of teeth, with a pawl having twoteeth one of which engages the teeth of said ratchet during a normalrotation of the shaft to hold the other pawl tooth disengaged from theratchet teeth, and said other 'pawl tooth engaging a tooth of theratchet to prevent a rotation of the shaft in a directionopposite tosaid normal rotation, and means for holding said pawl out of engagementwith said ratchet to permit it to rotate in a'direction opposite to itsnormal rotation.

10. The combination of a shaft having a ratchet wheel mounted thereon,said ratchet wheel having a plurality of teeth, with a pawl having twoteeth, one of which engages the teeth of said ratchet during a normalrotationof the shaft to hold the other pawl tooth disengaged from theratchet teeth, and said other pawl tooth engaging a tooth of the ratchetto prevent a rotation of said shaft in a direction opposite to itsnormal rotation, means for holding said pawl out of en- 7 gagement withsaid ratchet to permit the shaft to rotate in a direction opposite toits normal rotation, and means controlled by said latter rotation forlocking said pawl disengaged until said shaft is again rotated in itsnormal direction.

.11. In a motor vehicle, a transmission casing containing a shaft whichprojects through one of its walls, a plurality of gears for rotatingsaid shaft, a ratchet rigidily attached to said shaft,

a pawl normally engaging said ratchet to prevent a rotation of saidshaft in one direction, means for disengaging said pawl to permitrotation of said shaft in said one direction, and means disposedconcentrically around said shaft between said ratchet and casing wallfor holding said pawl disengaged.

12. In a motor vehicle, a transmission casing containing a shaft whichprojects through one of its walls, a plurality of gears for rotatingsaid shaft, a ratchet wheel disposed Within said casing and rigidlyattached to said shaft, a pawl normally engaging said ratchet wheel toprevent a rotation of said shaft in one direction, means for disengagingsaid pawl to permit rotation of said shaft in said one direction, and alocking disc concentrically disposed around said shaft in frictionalengagement withsaid ratchet for holding said pawl disengaged,

13. In a motor vehicle, a transmission casing locking discconcentrically disposed around said shaft in frictional engagement withsaid ratchet and rotated thereby to hold said pawl disengaged.

14. In a motor vehicle, a transmission casing containing a shaft whichprojects through one of its walls and a plurality of gears for rotatingsaid shaft, a ratchet wheel disposed within said casing and rigidlyattached to said shaft, a pawl normally engaging said ratchet to preventa rotation of said shaft in one dirertion, means for disengaging saidpawl to permit rotation of said shaft in said one direction, an ear onsaid pawl, a locking disc held in frictional engagement with saidratchet and arranged to be rotated by a rotation of it in said onedirection to engage said ear and thereby hold said pawl disengaged.

15. In a motor vehicle, atransmission casing containing a shaft whichprojects through one Of its walls and a plurality of gears for rotatingsaid shaft, a ratchet wheel disposed within said casing and rigidlyattached to said shaft, a pawl normally engaging said ratchet to preventa rotation of said shaft in one direction, means for disengaging saidpawl to permit rotation of. said shaft in said one direction, a lockingdisc disposed around said shaft, a ball race in one face i of said disc,a second ball race held stationary by dowelsprojecting into pockets insaid casing on said pawl engaged by said rotated disc to hold the pawldisengaged from said ratchet.

16. In a motor vehicle, the combination of a transmission having gearsselectively engaging a shaft to drive the vehicle in forward and reversedirections, with means including a member immovably fastened on saidshaft and a movable member cooperating therewith for preventing reversemovement of the vehicle when the gears are set to drive it forward,means actuated by a setting of said gears to drive the vehicle in areverse direction for moving said movable meme ber out of cooperativerelation with said shaft member, and means controlled by a reversemovement of the vehicle for holding said movable member out ofcooperative relation with said shaft member until the shaft rotates in aforward direction.

ROBERT LAPSLEY.

